The present invention relates to an electron beam lithography method which is used in a lithography process serving as a patterning process of a semiconductor device and an apparatus therefor.
For example, there has been proposed an electron beam lithography apparatus which can perform the patterning operation for a memory device with a high accuracy.
A lithography method used in the electron beam lithography apparatus is employed, in the case of fabricating an application specific integrated circuit (ASIC) or the like, as a direct writing technology for directly fabricating a device without using a mask or a mask lithography method for fabricating a mask itself. This electron beam lithography apparatus is suitable for accurate delineating or writing but is disadvantageous in that, when the apparatus is applied to fabrication of devices on a mass or volume production basis, its throughput is low unlike an optical aligner system. That is, since the electron beam lithography apparatus based on a variable shaped beam method requires to successively divide a device pattern to be written into rectangles and write the rectangles by using a variable shaped beam transfer mask. As a consequence, the number of necessary shots is remarkably increased and thus lots of time is required for processing.
In order to reduce the shot number in the electron beam lithography apparatus, there has been suggested a cell projection (one shot exposure lithography) method. In this method, noting the repeatability of devices, a cell as the repetitive pattern unit is used as a transfer mask and the transfer mask is used also as a variable shaped beam transfer mask, thereby reducing the shot number remarkably and increase a lithography throughput. One of such cell projection lithography technique is a pattern writing method as described, for example, in JP-A-4-148531.